1. Field of the Invention
This invention relates generally to inkjet printing. More particularly, this invention relates to a method used to control one or more printheads in an inkjet printer, and to an inkjet printer utilizing this method.
2. Related Technology
Inkjet printers or plotters typically have a print cartridge mounted on a carriage. This carriage is traversed back and forth across the width of a print medium (i.e., usually paper or a plastic plotting film, for example) as the print medium is fed through the printer or plotter. Plural orifices on the print cartridge are fed ink (or other printing fluid) by one or more channels communicating from a reservoir of the print cartridge. Energy applied individually to addressable resistors (or other energy-dissipating elements, for example, to piezoelectric actuators), transfers energy to printing fluid; which is within or associated with selected ones of the plural orifices. These orifices then eject printing fluid onto the printing medium.
Presently, it is conventional that when a new printhead technology is developed older printers are replaced with new printers that are able to use the new printhead technology. This is due to the conventional practice of using a control circuit in conventional printers that is a print formatter and printhead controller circuit. This control circuit, which is of a proprietary nature to each printer or family of printers, receives high level printing signals, and produces the control signals necessary not only to control the actions of the printer (i.e., movements of the print medium, and of the printhead carriage relative to this medium), but also controls the actions of the print cartridge itself. Thus, no two printer models, or only a family of printer models, even those manufactured by the same company, are compatible and can use printheads interchangeably. Theretofore it has not been practical to update existing printers with new printheads of new and improved technology because the new printhead would require control signals that simply could not be provided by the old formatter and printhead controller circuit.
Viewing now PRIOR ART FIG. 12, it is seen that in a conventional ink jet printer 500, all of these actions of the printer are controlled by a combination print formatter and printhead controller circuit 502; which receives high-level printing signals and printing data (represented by arrow 504), and transforms this high-level printing signals and data from the high-level language of the host computer (or other printing data source—not shown in the drawing Figures) into those discreet-event commands which control not only the firing sequence of the orifices of a printhead (i.e., the printing fluid ejection events) but also the position of the printhead(s), the movement of paper or other printing medium through the printer, etc.
Viewing FIG. 12 in greater detail, it is seen that a communication channel 504 (i.e., a printer cable, for example) exists between a sending device or other originator or source of high-level printing data and signals (such as a personal computer or other host computer system), and a conventional printer 500 having a combination print formatter and printhead controller circuit 502. The communication channel 504 facilitates the communication of the high-level printing signals 502 to the printer 500. This communication channel 500 may be a direct linkage between the host system and the print formatter and printhead controller circuit 502, or the communication channel may be effected through intermediate devices, such as a network print server, or the printer 500 may simply include a memory cache such as is incorporated into many conventional printing devices (i.e., a print buffer). That is, some part of, or all of the high-level print data and signals may be uploaded and stored in a print buffer memory cache until the combination print formatter and printhead controller circuit is ready to receive this communication. The print formatter and printhead controller circuit 502 then translates the signals 500 sent by the host system into a set of instructions that are conveyed to a printheads 506 of the printer 500 in a two way communication steam 508 such that the printhead 506 receives all necessary data for performing the print job and reports back such things as current position (i.e., horizontal and vertical position relative to the print medium), printhead temperature, and possibly an array of error messages to the control device, so that not only may the print formatter and printhead control circuit 502 keeps track of the position of the printhead 506, but also corrective action may be taken if any problems arise.
A long-standing challenge and deficiency in the manufacturing of such conventional inkjet printers 500 has been that when new improved printheads are developed and come on the market there is no easy or practical way to upgrade existing printers to utilize the new technology. This is the case because the print formatter and printhead controller circuit is able to provide control signals only for a particular one or limited family of printheads. As new printhead technology and new printheads become available, they require control signals that the print formatter and printhead controller circuit 502 cannot provide.